Fusible element for electric cut-outs.



R C. COLE.

FUSIBLE ELEMENT FOR ELECTRIC CUT-OUTS.

APPLICATION FILED JULY 30, HHS.

1 1 88, 1 52 Patented June 20, 1916.

8 1 WWI-1%} 7 UNITED STATES PATENT OFFICE.

ROBERT C. COLE, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE JOHNS-PRATT COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CONNECTICUT.

' FIJ'SIBLE ELEMENT FOR ELECTRIC CUT-OUTS.

Patented June 20, 1916.

Application filed July 30, 1915. Serial N 0. 42,854.

To ll whom it may concern:

Be.it knownv that I, ROBERT C. COLE, a citizen of the United States, residing at Hartford, in the county of'Hartford and State of Connecticut, have invented a new and useful Improvement in F usible Elements for Electric Cut-Outs, of which following is'a specification.

This invention relates to the constructiion of fusible links for inelosed fuses. It is desirable to have a fuse link disrupt and open the circuit at an exact predetermined time under overload conditions. This is particularly desirable on what is known as maximum load circuits, that is, circuits on which a customer ispermitted to use any desired amount of current up to a certain quantity, but no more. On such circuits the load usually increases very gradually, and where there is a gradual increase in overload a fuse link is liable to soften and perhaps melt and yet hang, that is, remain ina softened or liquidstate and still be a conductor capable of carrying current, al-

though the maximum has been exceeded.

The object of this invention is to provide mechanically operating means which will insure the rupture of the link and the opening of the circuit when the fusible metalbecomes melted or softened, and thus eliminate the possibility of the flow of a greater current than is intended, no matter how gradually the overload increases. To attain this end a spring is connected with the fusible element in such. manner that when the metal softens the spring owing to its resilience instantly causes the link to be ruptured.

Figure 1' of the accompanying drawings shows a plan of a fuse link constructed ae cording to this invention. Fig. 2 shows a side View of the same. Fig. 3 shows a link of modified form. Fig. 4 shows a side view of the modified form. Fig. 5 shows another modification. Fig. 6 shows a side view of the form shown in Fig. 5. Fig. 7 shows still another modification, and Fig. 8 shows a cross section of the modification shown in Fig. 7. p

These links may be used in any of the common types of inclosed and filled fuses with the 'usual casings and terminal conthe I be plain,

tacts. The link 1 may be made of any suit- 2 of suflicient size to carry the required cur-- rent. The links may be calibrated by a perforation 3, as shown in Fig. 1; or by notches 4, as shown in Fig. 3; or they may that is, without any calibration cuts, as shown in Fig. 5. Attached to the links are springs 5. These springs may be made of steel, phosphor-bronze, or any suitable metal "which will not lose its temper under such heat as is liable to be generated in the fuse. Thelsprings may be fastened to the links by rivets, as shown in Fig. 1; or they may be clipped to the links by parts 6 that are folded around the edges, as shown in Fig. 3.

Connected with the free end of the spring may be a stud 7 that passes through the link and has a head 8 on the other side which extends beneath the link in such manner that when the metal is softened by excess current the pull of the spring on the stud will cause the head to rupture the link. Instead of a stud a loop 9 may be used, as shown in Fig; 3, which loop is pulled by the spring so that when the metal is softened the link is ruptured. Instead of a pulling spring, such as is shown in Figs. 1 and 3, a pressing spring, of the character shown in Fig. 5, may be used, in which case the stud 10 may have a head 11 bearing down upon the link in such manner that when the metal is softened the spring will cause it to break apart. If desired, as shown in Figs. 7 and 8, an expansion spring 12 may be thrust undercompression into the calibration perforation of a link in such manner that when the metal softens the arms of thekspring will throw out and rupture the lin a v A fusible element constructed in this manner may be calibrated for overload with great accuracy, and will open a circuit more exactly with a smaller overload than when 7 of the current.

The invention claimed is: I transversely upon the section that Will fuse A fusible element for inclosed electric when the current reaches the predetermined 10 cut-outs consisting of a link of metal adaptmaximum. ed to be fused when the current reaches a 5 predetermined maximum, and a metallic ROBERT COLE spring mounted upon and fastened to the Witnesses: fusible link adjacent tothe section which IIAZEL G. BRAINARD,

will be fused and arranged to exert tension DUNCAN C. HOOKER. 

